Use of pulse oximetry to predict in-hospital complications in normotensive patients with pulmonary embolism

Detection of pulmonary embolism severity using clinical characteristics, hematological indices, and machine learning techniques

INTRODUCTION

Pulmonary embolism (PE) is a cardiopulmonary condition that can be fatal. PE can lead to sudden cardiovascular collapse and is potentially life-threatening, necessitating risk classification to modify therapy following the diagnosis of PE. We collected clinical characteristics, routine blood data, and arterial blood gas analysis data from all 139 patients.

METHODS

Combining these data, this paper proposes a PE risk stratified prediction framework based on machine learning technology. An improved algorithm is proposed by adding sobol sequence and black hole mechanism to the cuckoo search algorithm (CS), called SBCS. Based on the coupling of the enhanced algorithm and the kernel extreme learning machine (KELM), a prediction framework is also proposed.

RESULTS

To confirm the overall performance of SBCS, we run benchmark function experiments in this work. The results demonstrate that SBCS has great convergence accuracy and speed. Then, tests based on seven open data sets are carried out in this study to verify the performance of SBCS on the feature selection problem. To further demonstrate the usefulness and applicability of the SBCS-KELM framework, this paper conducts aided diagnosis experiments on PE data collected from the hospital.

DISCUSSION

The experiment findings show that the indicators chosen, such as syncope, systolic blood pressure (SBP), oxygen saturation (SaO2%), white blood cell (WBC), neutrophil percentage (NEUT%), and others, are crucial for the feature selection approach presented in this study to assess the severity of PE. The classification results reveal that the prediction model's accuracy is 99.26% and its sensitivity is 98.57%. It is expected to become a new and accurate method to distinguish the severity of PE.

Smartphone camera oximetry in an induced hypoxemia study

Hypoxemia, a medical condition that occurs when the blood is not carrying enough oxygen to adequately supply the tissues, is a leading indicator for dangerous complications of respiratory diseases like asthma, COPD, and COVID-19. While purpose-built pulse oximeters can provide accurate blood-oxygen saturation (SpO₂) readings that allow for diagnosis of hypoxemia, enabling this capability in unmodified smartphone cameras via a software update could give more people access to important information about their health. Towards this goal, we performed the first clinical development validation on a smartphone camera-based SpO₂ sensing system using a varied fraction of inspired oxygen (FiO₂) protocol, creating a clinically relevant validation dataset for solely smartphone-based contact PPG methods on a wider range of SpO₂ values (70–100%) than prior studies (85–100%). We built a deep learning model using this data to demonstrate an overall MAE = 5.00% SpO₂ while identifying positive cases of low SpO₂ < 90% with 81% sensitivity and 79% specificity. We also provide the data in open-source format, so that others may build on this work.

Risk factors for postpartum sepsis: a nested case-control study

Background

The Majority (99%) of maternal deaths occur in low and middle-income countries. The three most important causes of maternal deaths in these regions are postpartum hemorrhage, pre-eclampsia and puerperal sepsis. There are several diagnostic criteria used to identify sepsis and one of the commonly used criteria is systematic inflammatory response syndrome (SIRS). However, these criteria require laboratory investigations that may not be feasible in resource-constrained settings. Therefore, this study aimed to develop a model based on risk factors and clinical signs and symptoms that can identify sepsis early among postpartum women.

Methods

A case-control study was nested in an ongoing cohort of 4000 postpartum women who delivered or were admitted to the study hospital. According to standard criteria of SIRS, 100 women with sepsis (cases) and 498 women without sepsis (controls) were recruited from January to July 2017. Information related to the socio-demographic status, antenatal care and use of tobacco were obtained via interview while pregnancy and delivery related information, comorbid and clinical sign and symptoms were retrieved from the ongoing cohort. Multivariable logistic regression was performed and discriminative performance of the model was assessed using area under the curve (AUC) of the receiver operating characteristic (ROC).

Results

Multivariable analysis revealed that 1–4 antenatal visits (95% CI 0.01–0.62).

, 3 or more vaginal examinations (95% CI 1.21–3.65), home delivery (95% CI 1.72–50.02), preterm delivery, diabetes in pregnancy (95% CI 1.93–20.23), lower abdominal pain (95% CI 1.15–3.42)) vaginal discharge (95% CI 2.97–20.21), SpO2 < 93% (95% CI 4.80–37.10) and blood glucose were significantly associated with sepsis. AUC was 0.84 (95% C.I 0.80–0.89) which indicated that risk factors and clinical sign and symptoms-based model has adequate ability to discriminate women with and without sepsis.

Conclusion

This study developed a non-invasive tool that can identify postpartum women with sepsis as accurately as SIRS criteria with good discriminative ability. Once validated, this tool has the potential to be scaled up for community use by frontline health care workers.

The assessment of acute pulmonary embolism severity using CT angiography features

Background

This study was conducted to detect the association between radiologic features of CT pulmonary angiography (CTPA) and pulmonary embolism severity index (PESI).

Methods

A total of 150 patients with a definite diagnosis of PE entered the study. The CTPA feature including obstruction index, pulmonary trunk size, presence of backwash contrast, septal morphology, right ventricular (RV) and left ventricular (LV) dimensions, and RV/LV ratio were examined. The severity of the PE was estimated using PESI. The association between CTPA indices and PESI was measured. Statistical analysis was conducted using the SPSS software. P value < 0.05 was considered as statistically significant.

Results

A positive correlation was detected between the obstruction index and PESI (r = 0.45, P < 0.05). Moreover, PESI was significantly higher in patients with a more dilated pulmonary trunk (r = 0.20, P < 0.05). The backwash contrast and abnormal septal morphology were significantly more common among patients with higher PESI (P < 0.05). However, no significant correlation was detected between RV, LV, RV/LV, and PESI. The most predictor of high-risk PE was dilated pulmonary trunk with an odds ratio of 4.4.

Conclusion

Higher Obstruction index, dilated pulmonary trunk, presence of backwash contrast, and an abnormal septal morphology can be associated with a higher PESI.

Evolution of Acute Pulmonary Embolism Management: Review Article

Acute pulmonary emboli are a major cause of morbidity and mortality and require prompt evaluation, diagnosis, and treatment. To date, anticoagulation using low molecular weight heparin or non-Vitamin K oral anticoagulants has been the mainstay of treatment in the subset of patients in whom pulmonary embolism does not compromise hemodynamics. On the other hand however, patients with massive pulmonary embolism and shock, thrombolytic therapy is necessary. This raises the question whether ultrasound-assisted catheter directed thrombolytic delivery might be superior to systemic administration. This review article aims to consolidate recent literature to help achieve a better understanding toward the utility of catheter directed therapy.

A Photoplethysmographic Signal Isolated From an Additive Motion Artifact by Frequency Translation

Acquiring a precise percentage of oxygen saturation (SpO2) from a finger-probe pulse oximeter is dependent on both artifact-free red and infrared photoplethysmoghaphic (PPG) signals. Nonetheless, in real-life situations, these PPG signals are corrupted by a motion artifact (MA) signal that is generated from either finger or hand movement. To resolve this MA interference, the cause of the adulteration of PPG signals by the MA signal is examined. The MA signal is found to behave like an additive noise. Additionally, the frequency responses of the MA and PPG signals show that these signals are in the same frequency band. Hence, instead of direct current, a sinusoidal wave alternating current is proposed to drive an LED source in order to shift the PPG frequency band away from the MA frequency band. Experimentally, a commercial finger-probe pulse oximeter is employed. To determine the performance of the presented scheme, the resulting PPG signals are compared with those from employing the old-fashioned LED-driving method. In addition, the accuracy is verified by computing the SpO2 value. The results reveal that the proposed approach successfully retains the fundamental morphologies of the PPG structures when motion occurs. Moreover, the calculated SpO2 values from the proposed technique provide an average error of approximately 1.4%, whereas the conventional method yields a mean error approximately 4.2%.

Coping with trauma and adversity among Palestinians in the Gaza Strip: A qualitative, culture-informed analysis

In this article, we propose that coping is not only an individual property but also a structural feature. Coping shapes what is referred to in social network theory as multiplex networks, which are based on relations with multiple functions, values and meanings. Focus groups with adult Palestinians were held and content analysed. Five main coping strategies were identified: (a) creating cultural and religious meaning; (b) individualism to collectivism; (c) normalization and habituation; (d) belonging, acceptance, expectation and readiness; and (e) social support. Participants also reported culture-specific expressions for indicating psychological distress. Implications for cultural informed clinical work are then discussed.

The Role of Electrocardiography in Follow up of Pulmonary Thromboembolism

Objective

Electrocardiography (ECG) is a simple, valuable and easily applicable test that can be used in supporting the diagnosis and assessing the severity of pulmonary thromboembolism (PTE). In this study, it was aimed to identify the role of ECG scoring in diagnosis and follow up of PTE in comparison with community acquired pneumonia (CAP).

Methods

Patients with the diagnosis of PTE and CAP were included in the study prospectively between January 2007 and January 2009. ECG scorings were evaluated by two different cardiologists by the method described by Daniel et al at admission (day 0) and day 3, 10 and one month of treatment. Median values of ECG scorings were compared between days and between groups.

Results

Forty-five patients with PTE, 35 patients with CAP were included in the study. Although no statistically significant difference was identified between the ECG scorings of the two groups in each measurement point, ECG scores decreased more rapidly in PTE group within days. Within the PTE group, day 0 ECG score was identified higher in submassive patients than nonmassive ones (p=0.001).

Conclusions

Although ECG score did not differentiate PTE from CAP, depending on its rapid decrease in PTE, it can be used in the follow up. For submassive PTE patients that must be diagnosed and treated immediately, ECG scorings can be used to support the diagnosis and to assess the clinical severity.

Is oxygen saturation variable of simplified pulmonary embolism severity index reliable for identification of patients, suitable for outpatient treatment

INTRODUCTION

The pulmonary embolism severity index (PESI) or simplified version (sPESI) are widely validated risk scores for the identification of eligible patients for outpatient treatment. Saturation is one of these criteria. For this metric, saturation of 90% or greater is assigned zero points. However, 90% saturation does not always exclude hypoxemic respiratory failure.

OBJECTIVE

The aims of this study were first was to define corresponding partial arterial oxygen pressure (PaO₂ ) values according to saturation in pulmonary embolism (PE) patients, and the second was to define a target saturation that can exclude hypoxemic respiratory failure and enable secure discharge of PE patients from emergency departments.

METHODS

This is a retrospective study. To determine the optimal saturation value by which to detect hypoxemic respiratory failure, we generated receiver operating characteristic (ROC) curves and calculated the negative predictive value.

RESULTS

Total of 65 patients were included in this study. Mean PaO₂ levels from SaO₂ 89% to SaO₂ 93% were 52.8, 57.1, 57.3, 61, and 63.8 mmHg, respectively. ROC curve analysis revealed SaO₂ level of 91.5% to be optimal target saturation for excluding respiratory failure with 84.6% specificity and 89.7% sensitivity; area under the curve was 0.885 (95% CI 0.796-0.975). The negative predictive value was 80% for SaO₂ level of 92%.

CONCLUSION

Patients with PE may be in respiratory failure despite an oxyhemoglobin saturation of ≥90%. Although saturation is likely more important than precise PaO₂ in tissue oxygenation, clinicians should be aware of the physiological effects of hypoxemia and take this into account before making outpatient treatment decisions.

Pulse oximetry in bronchiolitis: is it needed?

Infants admitted to health-care centers with acute bronchiolitis are frequently monitored with a pulse oximeter, a noninvasive method commonly used for measuring oxygen saturation. The decision to hospitalize children with bronchiolitis has been largely influenced by pulse oximetry, despite its questionable diagnostic value in delineating the severity of the illness. Many health-care providers lack the appropriate clinical fundamentals and limitations of pulse oximetry. This deficiency in knowledge might have been linked to changes in the management of bronchiolitis. The aim of this paper is to provide the current evidence on the role of pulse oximetry in bronchiolitis. We discuss the history, fundamentals of operation, and limitations of the apparatus. A search of the Google Scholar, Embase, Medline, and PubMed databases was carried out for published articles covering the use of pulse oximetry in bronchiolitis.

Innovation and translation efforts in wireless medical connectivity, telemedicine and eMedicine: a story from the RFID Center of Excellence at the University of Pittsburgh

Translational research has recently been rediscovered as one of the basic tenants of engineering. Although many people have numerous ideas of how to accomplish this successfully, the fundamental method is to provide an innovative and creative environment. The University of Pittsburgh has been accomplishing this goal though a variety of methodologies. The contents of this paper are exemplary of what can be achieved though the interaction of students, staff, faculty and, in one example, high school teachers. While the projects completed within the groups involved in this paper have spanned other areas, the focus of this paper is on the biomedical devices, that is, towards improving and maintaining health in a variety of areas. The spirit of the translational research is discovery, invention, intellectual property protection, and the creation of value through the spinning off of companies while providing better health care and creating jobs. All but one of these projects involve wireless radio frequency (RF) energy for delivery. The remaining device can be wirelessly connected for data collection.

Causes of sudden unexpected death of adult hospital patients

The sudden unexpected death of a hospitalized patient is distressing to the family and the healthcare team. It is also common. Assessment of the causes without autopsy is frequently incorrect. To elucidate the causes of death, 175 cases of adult hospital patients in the University of Pittsburgh Medical Center Health System, who died suddenly and unexpectedly, were investigated with autopsies. The most common cause was judged to be a cardiac arrhythmia, in 58 (33%) of cases, presumptive in 46 cases, because only 12 of these patients were on cardiac monitoring. Of the arrhythmia patients, 36 (62%) had ≥75% coronary artery stenosis and 31 (53%) had histological evidence of myocardial infarction, with 15 (26%) of those with subacute or old myocardial infarction lacking a history of myocardial infarction. Hemorrhage was judged the cause of death in 38 (22%) of cases, including 31 (82%) with endogenous coagulopathy, anticoagulation, or antiplatelet therapy. Pulmonary thromboembolism was judged the cause of death in 27 (15%) of cases. Overall, hemorrhage deserves better appreciation as a cause of sudden unexpected death of hospitalized adults.

Pulmonary embolism

Pulmonary embolism (PE) remains one of the most challenging medical diseases in the emergency department. PE is a potentially life threatening diagnosis that is seen in patients with chest pain and/or dyspnea but can span the clinical spectrum of medical presentations. In addition, it does not have any particular clinical feature, laboratory test, or diagnostic modality that can independently and confidently exclude its possibility. This article offers a review of PE in the emergency department. It emphasizes the appropriate determination of pretest probability, the approach to diagnosis and management, and special considerations related to pregnancy and radiation exposure.

Risk stratification and clinical outcomes in patients with acute pulmonary embolism

OBJECTIVES

Pulmonary embolism is a common disease associated with a high mortality rate. The risk assessment and appropriate treatment selection of patients with acute pulmonary embolism remains a challenge.

DESIGN AND METHODS

This single center cohort study included a total of 150 patients (96 male, age = 71 ± 15 years) with acute pulmonary embolism confirmed by spiral-computed tomography or magnetic resonance image. The prognostic performance of the clinical characteristics and laboratory values were investigated to predict the in-hospital hemodynamically instable events and 30-day all-cause mortality.

RESULTS

The rate of in-hospital hemodynamic instability and 30-day all-cause mortality was 21% and 12%, respectively. A multivariate Cox regression analysis demonstrated that a heart rate ≥ 110 bpm (odd ratio 4.26 [95% CI 1.42-12.77]), chronic pulmonary disease (6.47 [1.99-21.04]), WBC ≥ 11,000 mm(3) (3.78 [1.32-10.82]), and D-dimer level ≥ 4.0 μg/mL (3.68 [1.01-13.43]) independently predicted the 30-day fatal outcome. A Kaplan-Meier survival analysis showed that the categorization based on the number of risk factors was significantly associated with the likelihood of 30-day all-cause mortality (P<0.0001).

CONCLUSIONS

The initial presentation of tachycardia, presence of chronic pulmonary disease, elevated WBC and D-dimer on admission can be used to identify the risk for a short-term fatal outcome within 30 days in patients with acute pulmonary embolism.

Management of massive and submassive pulmonary embolism, iliofemoral deep vein thrombosis, and chronic thromboembolic pulmonary hypertension: a scientific statement from the American Heart Association

Venous thromboembolism (VTE) is responsible for the hospitalization of >250 000 Americans annually and represents a significant risk for morbidity and mortality. Despite the publication of evidence-based clinical practice guidelines to aid in the management of VTE in its acute and chronic forms, the clinician is frequently confronted with manifestations of VTE for which data are sparse and optimal management is unclear. In particular, the optimal use of advanced therapies for acute VTE, including thrombolysis and catheter-based therapies, remains uncertain. This report addresses the management of massive and submassive pulmonary embolism (PE), iliofemoral deep vein thrombosis (IFDVT),and chronic thromboembolic pulmonary hypertension (CTEPH). The goal is to provide practical advice to enable the busy clinician to optimize the management of patients with these severe manifestations of VTE. Although this document makes recommendations for management, optimal medical decisions must incorporate other factors, including patient wishes, quality of life, and life expectancy based on age and comorbidities. The appropriateness of these recommendations for a specific patient may vary depending on these factors and will be best judged by the bedside clinician.

Current treatment of venous thromboembolism

Venous thromboembolism, comprising deep vein thrombosis and pulmonary embolism, is a common disorder with at least 250 000 new events occurring each year in the United States alone. Treatment of venous thromboembolism includes anticoagulation, which is achieved initially with the use of a parenterally administered agent followed by a more prolonged course of treatment with an oral vitamin K antagonist. The duration of treatment depends on the clinical assessment of the benefit-to-risk ratio of prolonged anticoagulation versus the risk of recurrent events. In this review, we discuss some of the issues that we believe are among the most critical unanswered questions in the management of venous thromboembolism in the present era.

Pulse oximetry in family practice: indications and clinical observations in patients with COPD

PURPOSE

To establish situations in which family physicians (FPs) consider pulse oximetry a valuable addition to their clinical patient assessment; to explore pulse oximetry results (SpO(2)) when used by FPs in patients with chronic obstructive pulmonary disease (COPD); to explore associations between SpO(2) and other markers of COPD severity.

METHODS

We performed three separate studies: (i) interviews plus a Delphi consensus procedure with FPs experienced in using pulse oximetry to elucidate indications for pulse oximetry; (ii) analysis of SpO(2) and clinical data in COPD patients who presented to FPs with deteriorating symptoms and (iii) analysis of SpO(2), spirometry and clinical data in patients with stable COPD.

RESULTS

Interviewed FPs (n = 11) used their pulse oximeter for a range of acute (14) and non-acute (11) indications but valued it highest in acute (worsening of) dyspnoea, in suspected respiratory insufficiency/failure and in patients with COPD. In 88 patients with deteriorating COPD, 22% showed SpO(2) <or=92%. Correlation between baseline forced expiratory volume in 1 second % predicted and SpO(2) in patients presenting with acute COPD exacerbations was r = 0.55 (P = 0.001). In 207 patients with stable COPD, 6.3% showed SpO(2) values <or=92%. SpO(2) values were associated with Medical Research Council dyspnoea scores (P = 0.019).

CONCLUSIONS

FPs report a wide range of indications for pulse oximetry in acute as well as non-acute situations. In COPD, pulse oximetry appears to be especially useful in patients with severe disease and worsening of symptoms. Pulse oximetry may have a role in the monitoring of patients with COPD with exercise-related dyspnoea.

Pulmonary embolism risk stratification: pulse oximetry and pulmonary embolism severity index

BACKGROUND

Risk stratification of pulmonary embolism (PE) patients is important to determine appropriate management.

OBJECTIVES

We evaluated two published risk-stratification tools in emergency department (ED) PE patients: a pulse oximetry cutoff below 92.5% oxygen (at 5280 feet elevation) and the Pulmonary Embolism Severity Index (PESI).

METHODS

Electronic medical records of all patients diagnosed with PE were abstracted to identify their triage vital signs, co-morbidities, and adverse short-term outcomes (AO) either requiring interventions (defined as respiratory failure, hypotension requiring pressors, and hemodynamic impairment requiring thrombolytics) or resulting in death. We applied these models to our ED PE patients and assessed their performance.

RESULTS

There were 168 PE patients identified, with an overall AO rate of 7.1% (12/168), including a 3.0% mortality rate. A room-air pulse oximetry cutoff of 92.5%, for values measured at 5280 feet, classified 89/136 patients as low risk, 1.1% of which had an AO, and 47/136 patients as high risk, of which 10.6% had AO. This pulse oximetry cutoff had a sensitivity of 83% (95% confidence interval [CI] 36-99%), specificity of 68% (95% CI 58-76%), and a negative predictive value (NPV) of 99% (95% CI 93-100%). PESI classified 91/168 patients as low risk (class I or II): 2.2% had AO but none died, and 77/168 were classified as high risk (class III, IV, or V), with an AO rate of 13.0%. A PESI cutoff score of II had a sensitivity of 83% (95% CI 52-98%), specificity of 57% (95% CI 49-65%), and NPV of 98% (95% CI 92-100%).

CONCLUSION

Both PESI and pulse oximetry measurements are moderately accurate identifiers of low-risk patients with PE.

Risk stratification and outcomes in hemodynamically stable patients with acute pulmonary embolism: a prospective, multicentre, cohort study with three months of follow-up

BACKGROUND

The role of risk stratification in normotensive patients with acute pulmonary embolism (PE) is still unclear.

OBJECTIVES

We evaluated, in these patients, the usefulness of six prognostic markers for predicting in-hospital adverse events related to PE and 3-month mortality.

PATIENTS/METHODS

Two hundred and one consecutive patients with confirmed acute PE and normal blood pressure, who were administered conventional anticoagulation, were recruited in a multicentre prospective cohort study with 3 months of follow-up. At baseline, they received a comprehensive risk-evaluation including echocardiographic assessment of right ventricular dysfunction, determination of troponin I, brain natriuretic peptide and D-dimer, arterial blood gas analysis and a clinical score. Primary outcome of the study was PE-related in-hospital death or clinical deterioration. Secondary outcomes were in-hospital and 3-month all-cause mortality.

RESULTS

The primary outcome occurred in one patient (0.5%), who died from PE during hospitalization. The in-hospital and 3-month all-cause mortality were 2% and 9%, respectively. None of the prognostic markers was predictive of the primary outcome. Clinical score, troponin I and hypoxemia predicted in-hospital all-cause mortality (P = 0.02, 0.01 and < 0.01, respectively). Clinical score (HR, 4.7; 95% CI, 1.9-12.0), D-dimer (4.8; 1.4-16.3), hypoxemia (5.7; 2.1-15.1) and troponin I (7.5; 2.5-22.7) were predictors of 3-month all-cause mortality on univariate analysis. On multivariate analysis clinical score and troponin I remained independently predictive.

CONCLUSIONS

We did not find prognostic markers useful as predictors of in-hospital PE-related adverse events. Clinical score, troponin I and hypoxemia predicted in-hospital all-cause mortality. Clinical score and troponin I independently predicted 3-month all-cause mortality.

Changes in oxidative stress haemostatic parameters during the thrombolytic treatment of pulmonary embolism

A pulmonalis embolia a harmadik leggyakoribb cardiovascularis halálok. A masszív tüdőembólia thrombolysiskezelése kapcsán vérzéses szövődmény, reembólia léphet fel, a kórállapotot oxidatív stressz kíséri. Célok: Vizsgálatunkban az akut tüdőembólia rögoldó kezelése során elemeztük a thrombocytaaggregáció, a haemostaseologiai paraméterek, a leukocytaaktiváció és az oxidatív stressz markereinek változásait. Módszer: 15 beteget választottunk be, akik ultranagy dózisú sztreptokináz- ( n = 8) vagy altepláz- ( n = 7) kezelésben részesültek. Artériás vérmintát vettünk a thrombolysis előtt, azt követően pedig az első 24 órában 4 óránként, majd a 36. órában, és a 2., 3., 4., 5. és 30. napon. Mértük a spontán és az adrenalin, a kollagén és az adenozin-difoszfát indukálta thrombocytaaggregációt. A D-dimer- és fibrinogénszinteket az első napon 8 óránként, majd a fenti időpontokban egy alkalommal vizsgáltuk. Az oxidatív stressz és a leukocytaaktiváció elemzésére a thrombolysis előtt, a kezelést követően a 8. órában, majd az 1., 3., 5. és 30. napon vettünk vérmintákat. Az oxidatív stressz változásának nyomon követésére plazmából és teljes vérből malondialdehid, redukált glutation-, plazmaszulfhidrilcsoport-szinteket, szuperoxid-dizmutáz- és mieloperoxidázenzim-aktivitást mértünk. A teljes vér gyöktermelő kapacitását, vizsgálatát kemilumineszcenciával végeztük. Áramláscitometriával mértük a leukocyták által expresszált CD11a, CD18 és CD97 felszíni antigéneket. Eredmények: Az adrenalin indukálta thrombocytaaggregáció a 4. és a 8. órában csökkent ( p < 0,03), és szignifikánsan alacsony tartományban maradt a 36. órától a 3. napig az alteplázcsoporthoz képest. A sztreptokinázzal kezelteknél az adenozin-difoszfát indukálta aggregáció a 4. órában csökkent a kiindulási értékhez képest ( p < 0,05), kollagén esetében ugyanez a csökkenés a 4. és a 8. órában szignifikáns. A fibrinogénszintek a thrombolysist követően mindkét kezelési csoportban szignifikánsan csökkentek, míg a D-dimer a 8. órában szignifikánsan megemelkedett. Spontán thrombocytaaggregációt egyetlen mérési időpontban sem találtunk, jelentős vérzés, reembólia nem lépett fel. Az emelkedett malondialdehid-, reaktívoxigéngyök- és mieloperoxidáz-szintek, a csökkent redukált glutation- és plazmaszulfhidril-szintek a tüdőembóliás betegekben jelen lévő fokozott oxidatív stresszre utalnak. A thrombolysist követően a malondialdehid szignifikánsan emelkedik, a redukált glutation pedig csökken. A reaktív oxigéngyökök termelése a 3. és 5. nap között a legmagasabb. A thrombolysist kifejezett granulocyta és monocyta CD11a- és CD18-, valamint granulocyta CD97-expresszió-csökkenés kíséri ( p < 0,05). Következtetések: A masszív/szubmasszív pulmonalis embolia és az alkalmazott thrombolysis károsítja a thrombocytafunkciókat. A tüdőembólia reperfúziója során a fibrinogénszint csökkenése szignifikáns korrelációt mutat a tüdőperfúzió javulásával, ezek alapján a fibrinogénszint változása jól alkalmazható marker lehet a thrombolysis eredményességének akut felmérésére. Masszív/szubmasszív pulmonalis emboliás betegeknél a thrombolysis előtt fokozott oxidatív stressz állt fenn. Igazoltuk, hogy TL-t követően az oxidatív stressz és a leukocytaaktiváció még kifejezettebb, és e paraméterek csak a 30. napra normalizálódnak.

Study on the error in the dynamic spectrum method relative with the pathlength factor as a function of wavelength

Utilizing near-infrared spectroscopy for non-invasive blood component concentration sensing has been a focusing topic in biomedical optics applications. The ease of use, low cost and portability of these methods is a clear advantage over the invasive blood component concentration sensing which is the main sensing method in the clinic application. However, there is no report about any successful non-invasive blood components (except the artery blood oxygen saturation) concentration detection techniques that can meet the requirements of clinic application. One of the most key difficulties is the influence of the individual discrepancy. Dynamic spectrum (DS) is a new measure method of non-invasive blood components concentration sensing presented recently. It can eliminate the individual discrepancy of the tissues except the pulsatile component of the artery blood (PCAB) theoretically. This indicates a brand new way to measure the blood components concentration and a potential to provide absolute quantitation of hemodynamic variables. One of the systematic errors in the calculation of the component changes from NIRS data of the dynamic spectrum is the absolute magnitudes and relative differences in pathlength factors as a function of wavelength. Monte Carlo simulations are used in this paper to examine the importance and mitigation methods of this error while the photoelectric pulse wave is detected on the finger tip. We found wavelength selection to be important variables in minimizing such errors, and replacing the average pathlength factor with the subsection pathlength factor appropriately could reduce the error to a small fraction (10%).

Surrogate markers for adverse outcomes in normotensive patients with pulmonary embolism*

BACKGROUND

Although echocardiography has proven utility in risk stratifying normotensive patients with pulmonary embolism, echocardiography is not always available.

OBJECTIVE

Test if a novel panel consisting of pulse oximetry, 12-lead electrocardiography, and serum troponin T would have prognostic equivalence to echocardiography and to examine the prognostic performance of age, previous cardiopulmonary disease, D-dimer, brain natriuretic peptide, and percentage of pulmonary vascular occlusion on chest computed tomography.

DESIGN

Prospective cohort study.

PATIENTS AND SETTING

Normotensive (systolic blood pressure of >100 mm Hg) emergency department and hospital inpatients with diagnosed pulmonary embolism who underwent cardiologist-interpreted echocardiography and other measurements within 15 hrs of anticoagulation.

MEASUREMENTS AND MAIN RESULTS

End points were in-hospital circulatory shock or intubation, or death, recurrent pulmonary embolism, or severe cardiopulmonary disability (defined as echocardiographic evidence of severe right ventricular dysfunction with New York Heart Association class III dyspnea or 6-min walk test of <330 m) at 6-month follow-up. The two-one-sided test tested the hypothesis of equivalence with one-tailed alpha = 0.05 and Delta = 5%. Of 200 patients enrolled, data were complete for 181 (88%); 51 of 181 patients (28%) had an adverse outcome, including in-hospital complication (n = 18), death (n = 11), recurrent pulmonary embolism (n = 2), or cardiopulmonary disability (n = 20). Right ventricular dysfunction on initial echocardiogram was 61% sensitive (95% confidence interval, 46-74%) and 57% specific (48-66%). The panel was 71% sensitive (56-83%) and 62% specific (53-71%). The two-one-sided procedure demonstrated superiority of the panel to echocardiography for both sensitivity and noninferiority for specificity. No other biomarker demonstrated equivalence, noninferiority, or superiority for sensitivity and specificity.

CONCLUSION

Normotensive patients with pulmonary embolism have a high rate of severe adverse outcomes during 6-month follow-up. A panel of three widely available tests can be used to risk stratify patients with pulmonary embolism when formal echocardiography is not available.

Estimating the pretest probability threshold to justify empiric administration of heparin prior to pulmonary vascular imaging for pulmonary embolism

Expertly interpreted pulmonary vascular imaging (either ventilation-perfusion scan or computed tomography chest angiography) is not uniformly available at most hospitals, including those in the US. When evaluating a patient with suspected pulmonary embolism during times when pulmonary vascular imaging is not available, clinicians frequently face the decision of whether to administer heparin while awaiting availability of imaging. In this report, we analyze published data to quantitate the probability of death or disability from untreated pulmonary embolism versus the probability of serious bleeding for one, two and seven days of heparin therapy. For these three time points, we estimate the pretest probability of pulmonary embolism to justify the empiric administration of heparin.

Pretest probability assessment derived from attribute matching

Background

Pretest probability (PTP) assessment plays a central role in diagnosis. This report compares a novel attribute-matching method to generate a PTP for acute coronary syndrome (ACS). We compare the new method with a validated logistic regression equation (LRE).

Methods

Eight clinical variables (attributes) were chosen by classification and regression tree analysis of a prospectively collected reference database of 14,796 emergency department (ED) patients evaluated for possible ACS. For attribute matching, a computer program identifies patients within the database who have the exact profile defined by clinician input of the eight attributes. The novel method was compared with the LRE for ability to produce PTP estimation <2% in a validation set of 8,120 patients evaluated for possible ACS and did not have ST segment elevation on ECG. 1,061 patients were excluded prior to validation analysis because of ST-segment elevation (713), missing data (77) or being lost to follow-up (271).

Results

In the validation set, attribute matching produced 267 unique PTP estimates [median PTP value 6%, 1^st–3^rd quartile 1–10%] compared with the LRE, which produced 96 unique PTP estimates [median 24%, 1^st–3^rd quartile 10–30%]. The areas under the receiver operating characteristic curves were 0.74 (95% CI 0.65 to 0.82) for the attribute matching curve and 0.68 (95% CI 0.62 to 0.77) for LRE.

The attribute matching system categorized 1,670 (24%, 95% CI = 23–25%) patients as having a PTP < 2.0%; 28 developed ACS (1.7% 95% CI = 1.1–2.4%). The LRE categorized 244 (4%, 95% CI = 3–4%) with PTP < 2.0%; four developed ACS (1.6%, 95% CI = 0.4–4.1%).

Conclusion

Attribute matching estimated a very low PTP for ACS in a significantly larger proportion of ED patients compared with a validated LRE.

Impact of a rapid rule-out protocol for pulmonary embolism on the rate of screening, missed cases, and pulmonary vascular imaging in an urban US emergency department

STUDY OBJECTIVE

This study tests the hypothesis that implementation of a point-of-care emergency department (ED) protocol to rule out pulmonary embolism would increase the rate of evaluation without increasing the rate of pulmonary vascular imaging or ED length of stay and that less than 1.0% of patients with a negative protocol would have an adverse outcome.

METHODS

A baseline study was conducted on patients with suspected pulmonary embolism at an urban ED to establish baseline measurements performed when only pulmonary vascular imaging was available to rule out pulmonary embolism. The intervention protocol used pretest probability assessment, a whole-blood d -dimer assay, and an alveolar dead-space measurement to rule out pulmonary embolism. The main outcomes were diagnosis of venous thromboembolism or sudden unexpected death within 90 days.

RESULTS

During baseline, 453 of 61,322 patients (0.74%; 95% confidence interval [CI] 0.67% to 0.81%) underwent pulmonary vascular imaging, and 8% (95% CI 6% to 11%) of scan results were positive; 1.20% (95% CI 0.39% to 2.78%) of untreated discharged patients were anticoagulated for venous thromboembolism or died unexpectedly within 90 days. The median length of stay was 385 minutes. After intervention, 1,460 of 102,848 patients (1.42%; 95% CI 1.35% to 1.49%) were evaluated for pulmonary embolism. Seven hundred fifty-two patients had a negative protocol and 5 of 752 (0.66%; 95% CI 0.20% to 1.54%) had venous thromboembolism within 90 days, none with unexpected death. After intervention, the rate of pulmonary vascular imaging tended to decrease (0.64%; 95% CI 0.59% to 0.69%), and more scans (11%; 95% CI 9% to 14%) were read as positive; the length of stay decreased to 297 minutes.

CONCLUSION

A point-of-care pulmonary embolism rule-out protocol doubled the rate of screening for pulmonary embolism in the ED, had a false negative rate of less than 1.0%, did not increase the pulmonary vascular imaging rate, and decreased length of stay.